Update reveal.js version to 5.2.1 in README.md

Change-Id: I864323bfa93e3c2882082ef57714dbc743671f7b
diff --git a/README.md b/README.md
index 2d4b6b3..abb3c36 100644
--- a/README.md
+++ b/README.md
@@ -7,7 +7,7 @@
 [![CRAN
 status](https://www.r-pkg.org/badges/version/revealjs)](https://CRAN.R-project.org/package=revealjs)
 [![R-CMD-check](https://github.com/rstudio/revealjs/actions/workflows/R-CMD-check.yaml/badge.svg)](https://github.com/rstudio/revealjs/actions/workflows/R-CMD-check.yaml)
-[![reveal.js](https://img.shields.io/badge/reveal.js-4.6.1-yellow)](https://github.com/rstudio/revealjs/tree/main/inst/reveal.js-4.6.1)
+[![reveal.js](https://img.shields.io/badge/reveal.js-5.2.1-yellow)](https://github.com/rstudio/revealjs/tree/main/inst/reveal.js-5.2.1)
 <!-- badges: end -->
 
 ## Screenshots
@@ -26,7 +26,7 @@
 
 This repository provides an [R Markdown](http://rmarkdown.rstudio.com)
 custom format for [reveal.js](https://revealjs.com/) HTML presentations.
-The packages includes *reveal.js* library in version 4.6.1
+The packages includes *reveal.js* library in version 5.2.1
 
 You can use this format in R Markdown documents by installing this
 package as follows: